Is it valid to send an offer within an UPDATE if the INVITE's 18x answer was not sent requiring 100rel? Does the answer to the question change if the 18x was sent over TCP?
RFC 3261 section 13.2.1 could be interpreted that the answer can be within a 18x if it is received by the UAC. However RFC 3311's interpretation appears to require 100rel instead of just receiving the 18x. RFC 3261 section 13.2.1: "If the initial offer is in an INVITE, the answer MUST be in a reliable non-failure message from UAS back to UAC which is correlated to that INVITE. For this specification, that is only the final 2xx response to that INVITE. That same exact answer MAY also be placed in any provisional responses sent prior to the answer. The UAC MUST treat the first session description it receives as the answer, and MUST ignore any session descriptions in subsequent responses to the initial INVITE." "Concretely, the above rules specify two exchanges for UAs compliant to this specification alone - the offer is in the INVITE, and the answer in the 2xx (and possibly in a 1xx as well, with the same value), or the offer is in the 2xx, and the answer is in the ACK." RFC 3311 section 5.1: "If the UPDATE is being sent before completion of the initial INVITE transaction, and the initial INVITE contained an offer, the UPDATE can contain an offer if the callee generated an answer in a reliable provisional response, and the caller has received answers to any other offers it sent in either PRACK or UPDATE, and has generated answers for any offers it received in an UPDATE from the callee." "If the UPDATE is being sent before the completion of the INVITE transaction, and the initial INVITE contained an offer, the UPDATE cannot be sent with an offer unless the callee has generated an answer in a reliable provisional response, has received a PRACK for that reliable provisional response, has not received any requests (PRACK or UPDATE) with offers that it has not answered, and has not sent any UPDATE requests containing offers that have not been answered." _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
